Heat Stress Module overview: Difference between revisions
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The [[DPRA Heat Stress Module]] for the [[Heat Stress Overlay]] can be used for heat stress calculations, based on geographical features and locale parameters. The final result is the [[Pet result type (Heat Stress Overlay)|physiological equivalent temperature]], | The [[DPRA Heat Stress Module]] for the [[Heat Stress Overlay]] can be used for heat stress calculations, based on geographical features and locale parameters. The final result is the [[Pet result type (Heat Stress Overlay)|physiological equivalent temperature]], a measure that accounts for factors affecting the perception and impact of temperature. | ||
The module performs these calculations in accordance with the {{Heat DPRA Report}}. | The module performs these calculations in accordance with the {{Heat DPRA Report}}. | ||
[[File:Overview_Heat_Module.jpg | [[File:Overview_Heat_Module.jpg]] | ||
==Input factors== | ==Input factors== | ||
The calculation of the Heat Stress Overlays takes into account: | The calculation of the Heat Stress Overlays takes into account: | ||
* Meteorological circumstances such as: | * Meteorological circumstances such as: | ||
** Sun angles, [[ | ** Sun angles, [[Sun altitude (Heat Stress Overlay)|altitude]] and [[Sun azimuth (Heat Stress Overlay)|azimuth]], dependent on date and time of day and project location. | ||
** Air temperatures, ([[ | ** Air temperatures, ([[Hourly temperature (Heat Stress Overlay)|hourly]], [[Daily temperature min (Heat Stress Overlay)|daily minimum]] and [[Daily temperature max (Heat Stress Overlay)|maximum]]); | ||
** Global radiation, ([[ | ** Global radiation, ([[Hourly radiation (Heat Stress Overlay)|hourly]] and [[Daily avg radiation (Heat Stress Overlay)|average]]); | ||
** Relative humidity ([[ | ** Relative humidity ([[Hourly humidity (Heat Stress Overlay)|hourly]]); | ||
** Wind speeds ([[ | ** Wind speeds ([[Wind speed (Heat Stress Overlay)|hourly]] and [[Daily avg wind speed (Heat Stress Overlay)|daily average]]). | ||
** Wind direction ([[ | ** Wind direction ([[Wind direction (Heat Stress Overlay)|hourly]]) | ||
* Spatial situation, such as: | * Spatial situation, such as: | ||
** Land use, for fraction vegetation and rate of evaporation ([[ | ** Land use, for fraction vegetation and rate of evaporation ([[Bowen ratio (Heat Stress Overlay)|Bowen ratio]]). | ||
** Terrain, [[ | ** Terrain, [[Foliage crown factor (Heat Stress Overlay)|foliage]] and building heights | ||
==Calculation of Physiological Equivalent Temperature== | ==Calculation of Physiological Equivalent Temperature== | ||
To calculate the Physiological Equivalent Temperature (PET), we first have to determine which formula (''sun'' or ''shade/night'') should be used. | To calculate the Physiological Equivalent Temperature (PET), we first have to determine which formula (''sun'' or ''shade/night'') should be used. | ||
It is selected by: | It is selected by: | ||
* Day or night? Determined by the [[ | * Day or night? Determined by the [[Sun altitude (Heat Stress Overlay)|sun altitude angle]]; | ||
* Is a cell shaded? Calculated by the [[ | * Is a cell shaded? Calculated by the [[Shade calculation model (Heat Stress Overlay)|shade calculation model]]; | ||
===PET sun=== | ===PET sun=== | ||
The following factors influence the [[ | The following factors influence the [[PET formulas (Heat Stress Overlay)|Physiological Equivalent Temperature]] for locations directly in the sun: | ||
* The [[ | * The [[Temperature atmosphere result type (Heat Stress Overlay)|atmospheric temperature]], calculated by the [[Temperature formulas (Heat Stress Overlay)#Atmospheric Temperature formula|atmospheric temperature formula]]; | ||
* The [[ | * The [[Hourly radiation (Heat Stress Overlay)|hourly global radiation]] from the sun, supplied as weather station data; | ||
* The [[ | * The [[Wind speed result type (Heat Stress Overlay)|wind speed]] at 1.2 meter above ground, calculate by the [[Wind calculation model (Heat Stress Overlay)|wind speed calculation model]]; | ||
* The Wet-Bulb temperature, calculated by the [[ | * The Wet-Bulb temperature, calculated by the [[Temperature formulas (Heat Stress Overlay)#Wet-bulb Temperature formula|Wet Bulb temperature formula]]; | ||
* The [[ | * The [[Sun altitude (Heat Stress Overlay)|sun altitude]], calculated automatically based on the project area, date and time of day; | ||
* The [[ | * The [[Bowen ratio (Heat Stress Overlay)|Bowen ratio]], an attribute obtained from Buildings or Terrain on that specific location; | ||
* The [[ | * The [[Sky view result type (Heat Stress Overlay)|sky view factor]] and its [[Sky view avg result type (Heat Stress Overlay)|average]], calculated by the [[Sky view factor calculation model (Heat Stress Overlay)|sky view factor calculation model]]. | ||
===PET shade and night=== | ===PET shade and night=== | ||
The following factors influence the [[ | The following factors influence the [[PET formulas (Heat Stress Overlay)|Physiological Equivalent Temperature]] for locations directly in the shade or at night: | ||
* The [[ | * The [[Temperature atmosphere result type (Heat Stress Overlay)|atmospheric temperature]], calculated by the [[Temperature formulas (Heat Stress Overlay)#Atmospheric Temperature formula|atmospheric temperature formula]]; | ||
* The [[ | * The [[Wind speed result type (Heat Stress Overlay)|wind speed]] at 1.2 meter above ground, calculate by the [[wind calculation model (Heat Stress Overlay)|Wind speed calculation model]]; | ||
* The Wet-Bulb temperature, calculated by the [[ | * The Wet-Bulb temperature, calculated by the [[Temperature formulas (Heat Stress Overlay)#Wet-bulb Temperature formula|Wet Bulb temperature formula]]; | ||
* The [[ | * The [[Sky view result type (Heat Stress Overlay)|sky view factor]], calculated by the [[Sky view factor calculation model (Heat Stress Overlay)|sky view factor calculation model]]. | ||
* The diffuse radiation, calculated by the [[ | * The diffuse radiation, calculated by the [[Diffuse radiation formula (Heat Stress Overlay)|diffuse radiation formula]]. | ||
==Required information== | ==Required information== | ||
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* Daily [[Weather station (Heat Stress Overlay)|weather station]] data | * Daily [[Weather station (Heat Stress Overlay)|weather station]] data | ||
* Hourly weather station data | * Hourly weather station data | ||
* [[Foliage height | * [[Foliage height (Heat Stress Overlay)|Foliage height]] (although a [[foliage crown factor (Heat Stress Overlay)|means of estimation]] is available) | ||
==See also== | ==See also== | ||
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==Getting started with the Heat Module== | ==Getting started with the Heat Module== | ||
In order to get acquainted with configuring the Heat Overlay, follow our [[ | In order to get acquainted with configuring the Heat Overlay, follow our [[Tutorial Heat Stress Project|Heat Overlay Tutorial]] and/or the instructions on our . The process of configuring the Heat Overlay can be guided by the [[Heat Stress Overlay Wizard]]. | ||
====Date and time of day==== | ====Date and time of day==== | ||
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For each day, and for each time of day, the following will be automatically generated when using the wizard: | For each day, and for each time of day, the following will be automatically generated when using the wizard: | ||
# The day and time pairs, along with the project location, will be used to automatically calculate the sun altitude and azimuth angles for each day-time pair. | # The day and time pairs, along with the project location, will be used to automatically calculate the sun altitude and azimuth angles for each day-time pair. | ||
# The [[ | # The [[Sun daily motion (Heat Stress Overlay)|sun daily motion factor]] is a parameter used in the atmospheric temperature formula. It will be automatically selected from the sun motion factor table, based on the date (column) and time of day (row). | ||
====Weather station data==== | ====Weather station data==== | ||
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*'''Daily Values''' | *'''Daily Values''' | ||
# The [[ | # The [[Daily temperature min (Heat Stress Overlay)|minimum]] and [[Daily temperature max (Heat Stress Overlay)|maximum temperature]] of the day; | ||
# The [[ | # The [[Daily avg wind speed (Heat Stress Overlay)|average wind speed]], measured at the height of 10 meters; | ||
# The [[ | # The [[Daily avg radiation (Heat Stress Overlay)|average global sun radiation]] during sun hours; | ||
*'''Hourly Values''' | *'''Hourly Values''' | ||
# The [[ | # The [[Hourly temperature (Heat Stress Overlay)|hourly temperature]]; | ||
# The [[ | # The [[Hourly humidity (Heat Stress Overlay)|hourly humidity]]; | ||
# The [[ | # The [[Hourly radiation (Heat Stress Overlay)|hourly sun radiation]], as an average of the current and previous hour; | ||
# The [[ | # The [[Wind speed (Heat Stress Overlay)|hourly wind speed]]; | ||
# The [[ | # The [[Wind direction (Heat Stress Overlay)|hourly wind direction]]; | ||
====Foliage Height==== | ====Foliage Height==== | ||
Select what source will define the Foliage height: | Select what source will define the Foliage height: | ||
* Buildings with [[Function|functions]] related to foliage. The [[ | * Buildings with [[Function|functions]] related to foliage. The [[Foliage height calculation model (Heat Stress Overlay)|foliage height calculation model]] will determine the foliage height using the height of the vegetation (as buildings) and the foliage crown factor attribute; | ||
* Areas with as foliage height attribute, defining the foliage height for a whole area; | * Areas with as foliage height attribute, defining the foliage height for a whole area; | ||
* [[GeoTIFF]], defining a foliage height value for each cell in its raster. | * [[GeoTIFF]], defining a foliage height value for each cell in its raster. | ||
Latest revision as of 12:33, 7 July 2026
The DPRA Heat Stress Module for the Heat Stress Overlay can be used for heat stress calculations, based on geographical features and locale parameters. The final result is the physiological equivalent temperature, a measure that accounts for factors affecting the perception and impact of temperature.
The module performs these calculations in accordance with the DPRA Heat stress report.
Input factors
The calculation of the Heat Stress Overlays takes into account:
- Meteorological circumstances such as:
- Spatial situation, such as:
- Land use, for fraction vegetation and rate of evaporation (Bowen ratio).
- Terrain, foliage and building heights
Calculation of Physiological Equivalent Temperature
To calculate the Physiological Equivalent Temperature (PET), we first have to determine which formula (sun or shade/night) should be used. It is selected by:
- Day or night? Determined by the sun altitude angle;
- Is a cell shaded? Calculated by the shade calculation model;
PET sun
The following factors influence the Physiological Equivalent Temperature for locations directly in the sun:
- The atmospheric temperature, calculated by the atmospheric temperature formula;
- The hourly global radiation from the sun, supplied as weather station data;
- The wind speed at 1.2 meter above ground, calculate by the wind speed calculation model;
- The Wet-Bulb temperature, calculated by the Wet Bulb temperature formula;
- The sun altitude, calculated automatically based on the project area, date and time of day;
- The Bowen ratio, an attribute obtained from Buildings or Terrain on that specific location;
- The sky view factor and its average, calculated by the sky view factor calculation model.
PET shade and night
The following factors influence the Physiological Equivalent Temperature for locations directly in the shade or at night:
- The atmospheric temperature, calculated by the atmospheric temperature formula;
- The wind speed at 1.2 meter above ground, calculate by the Wind speed calculation model;
- The Wet-Bulb temperature, calculated by the Wet Bulb temperature formula;
- The sky view factor, calculated by the sky view factor calculation model.
- The diffuse radiation, calculated by the diffuse radiation formula.
Required information
In order to configure the Heat Stress Overlay accurately additional data needs to be loaded in:
- Date(s) and time of day. Also multiple consecutive days can be used. Each day-hour combination will become a result.
- Daily weather station data
- Hourly weather station data
- Foliage height (although a means of estimation is available)
See also
- Getting started (Heat Stress Overlay)
- Heat Stress Overlay Wizard
- Calculation models and formulas (Heat Stress Overlay)





